This invention concerns apparatus for turning over articles as they are being conveyed past a station. This may be done in order that an inspector is able to observe a reverse side of the article, as for example, board and lumber pieces conveyed sideways past a grader. Other conveyed articles such as doors, panels, etc., may need to be inverted for assembly or processing steps.
For many years, human lumber grade sorters stood at inspection stations next to a board conveyor and manually turned over the pieces passing by the station.
This manual operation was practical at the low speeds at which earlier conveyors operated, i.e., 40–50 pieces per minute.
Subsequently, conveyors have been speeded up to 100 or more pieces per minute. At these rates, a turnover apparatus is necessitated in order that human inspectors can carry out the grading tasks without undue physical stress.
Such apparatus has heretofore been developed which have been able to operate successfully with up to 100 pieces per minute.
See U.S. Pat. No. 6,446,785 B1 for an example of a currently available board turnover apparatus.
Even higher conveyor rates have now been achieved, i.e., 200 boards per minute or more, and a turnover apparatus and method capable of reliably achieving such rates has not heretofore been developed. This is believed to be because of the difficulties encountered in reliably synchronizing the turnover action of separately driven flipping mechanisms with the conveyor movement at these higher rates.
It is the object of the present invention to provide a turnover apparatus and method of the type described which is capable of reliably turning over conveyed articles such as boards at a rate substantially in excess of 100 articles per minute.